Battery-Powered deposition system and process for making reflective coatings

Abstract

A battery powered deposition system and process for applying aluminum, silver, and SiO films (and their derivatives such as aluminum oxide, aluminum nitride and silicon dioxide) especially for making broadband reflective coatings for mirrors. One or more filaments are wetted with a filament wetting material such as aluminum or a silver alloy. In a preferred embodiment filaments are heated quickly to a high temperature with an array of batteries and the filament wetting material is deposited as a reflective coating on the mirror.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of provisional application Ser. No. 62 / 388,546 filed 2016 Feb. 1, 2016.FIELD OF THE INVENTION[0002]The present invention relates to a new device and vacuum deposition processes to manufacture broadband reflective coatings for mirrors.BACKGROUND OF THE INVENTION[0003]Vacuum deposition refers to a family of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface. These processes operate at pressures at below atmospheric pressure (typically between 1×10−4 torr and 1×10−7 torr). The deposited layers can range from a thickness of one atom up to several microns. Multiple layers of different materials can be used to form protective coatings or optical interference coatings. Evaporation is a common method of thin-film deposition. Evaporation involves the heating of a source material, which evaporates and condenses on the target object (substrate). Performing the proc...

AI Technical Summary

Benefits of technology

The patent describes a process for making coatings that reflect light in a wide range of colors. The process uses small batteries to power filaments that contain the coating material. By controlling the rate at which energy is supplied to the filaments, the material is heated to the melting point and then heated more quickly by turning up the current to the filament. This prevents the filament from being over-energized when it is cold and has low resistance. A programmable circuit is used to accomplish the controlled release of electrical power to the filament. The process is stopped before all the aluminum is removed from the filament to minimize contamination on the mirror coating. A mechanical shutter is used to abruptly halt the deposition of material on the mirror substrate and prevent low-rate material from reaching the substrate. The patent also discusses a miniaturization of the deposition unit into something the size of a medicine bottle and as battery technology improves, the evaporation device could be reduced to the size of a wrist watch.

Problems solved by technology

However, filament evaporation severely limits the choices of materials that may be evaporated.

This limits the protective coating recipes that may be devised to prevent degradation of the silver reflector over time due to tarnishing.

Carrying low-voltage and high current over significant distances to many small evaporation sources would require heavy copper cables and large powers supplies, and is therefore less practical for coating in space.

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